# Tag Info

## New answers tagged plasma-physics

1

An ADC could convert the signal of a photo diode to a digital value which represents a random number that depends on the brightness of one position on the globe. But this would not make a good random generator because most likely a bright spot on the globe will still be bright after short time the rate random numbers per second is quite low the overall ...

0

The Fermi velocity, the Fermi momentum and the Fermi temperature are all really just ways of rewriting the Fermi energy, $E_F$. The Fermi energy is the energy f or a gas of fermions such that at 0 temperature all states with energy below $E_F$ are filled and all states with energy above $E_F$ are empty. Leaving aside the details of relativistic QM, a Fermi ...

1

I don't see an "equivalence between the partial and total derivative" of H in anything you've written; it's always written $dH/dt$ as a total derivative. The reason that the partials emerge within the volume integral is because A and B are also functions of space, and so the time derivative must be taken while holding position constant; it's basically that: ...

-4

Carbon is the only gas, when solidified, that can conduct electricity. This is of the form Graphite, when it only has 3 bonds between the atoms. This leaves electrons to flow through the network structure.

2

Yes, you do need to have electric field in order to get an ExB drift. As the name suggests, this will happen in the direction of the cross product of the electric and magnetic field. $\vec{v}_{E \times B} = \frac{\vec{E} \times \vec{B} }{B^2}$ This drift does not depend on the charge of particle, meaning that it will move both ions and electrons in the ...

1

I can't think of any practical reason to extract hydrogen from a star because it's so abundant and easier to get from say - Saturn, Uranus, even Titan. Any of the outer planets or moons with an atmosphere should have abundant hydrogen. The inner planets - not so much, but the outer planets have lots. Something to consider is that Solar energy alone is ...

3

So: fusing hydrogen to helium yields 0.7% of the hydrogen mass as energy. The amount of hydrogen required per second if you have a 100% efficient energy capture process and need the power of the Sun is $3.8\times 10^{26}/(0.007c^2) = 6\times10^{11}$ kg/s. Provided you can figure out how to process this (and that seems much harder than building a Dyson ...

0

The obvious order parameter is something like the fraction of atoms or molecules ionized, say "x'. Simple stat mech says that at any finite temperature that will be in the range (0,1). The question is whether, for some density of particles, there's a discontinuity as a function of T in either x (first order) or dx/dT (second order). There's a reason some ...

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